JP2009130969A - Flat brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat brushless motor which can materialize the avoidance of a dead point surely without deteriorating its torque performance at current application. <P>SOLUTION: This flat brushless motor is equipped with a stator magnetic plate 10, which mounts drive coils 42-45 and magnetic pole detecting elements around a pivot 30, and a rotor 100, in which an annular magnet 50 having N poles and S poles alternately in its circumferential direction at a fan-shaped magnetic pole face of 60° in circular angle is arranged in face opposition to the stator magnetic plate 10 and which is supported rotatably for the pivot 30. It is equipped with holes h<SB>1</SB>-h<SB>3</SB>for generation of cogging torque, which have their hole centers C<SB>1</SB>to C<SB>3</SB>in positions excluding a detection reference line m1 and parting lines m2 and m3, in a region which opposes by face the annular magnet 50 out of the stator magnetic plate 10, and hole edges F<SB>1</SB>to F<SB>3</SB>are formed on the inner side than the peripheral side edge 50b of the annular magnet 50. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flat brushless motor applicable to a flat vibration motor mounted on a mobile phone or the like.

  In the flat brushless motor disclosed in Japanese Patent Laid-Open No. 5-146134, as shown in FIG. 11, an annular magnet 1 having four magnetic poles and a magnet that is provided opposite to the magnet and functions as a yoke of the annular magnet 1. At the outer peripheral edge of the magnetic material plate 2, the Hall element 3 mounted on the plate 2 for detecting the rotational position of the rotor magnetic pole, the two drive coils 4 for applying rotational force to the rotor magnetic pole when energized, It has a notch portion 5 formed at a position excluding the position of the Hall element 3 and the position equally divided at 90 ° with respect to this. If the rotor magnetic pole stops just above the drive coil 4, that is, if the magnetic pole boundary (magnetic neutral point) L between the fan-shaped magnetic pole faces stops right above the Hall element 3, self-starting is impossible. However, when the rotor stops, the magnetic pole boundary L stops on the notch center line (symmetry axis) O of the notch 5 that generates the cogging torque. Since the magnetic pole face is located at the front end, the magnetic pole of the Hall element 3 can be detected, the rotor can be automatically started in the forward direction by re-energization, and a dead point can be avoided.

The shift angle θ from the position of the Hall element 3 to the notch center line O is twice or more larger than half of the notch occupation angle φ.
JP-A-5-146134 (FIGS. 3 and 4)

  However, the dead point avoidance technique has the following problems. That is, immediately before the rotor stops, in the state where the magnetic pole boundary line L is on the cutout portion 5, the magnetic pole boundary line L is kept until the magnetic attractive force of the magnetic force lines concentrated on the edge of the cutout portion 5 is just balanced. The magnetic pole boundary L stops substantially in alignment with the notch center line O of the notch 5, but immediately before the rotor stops, the central portion that is the main magnetism of the fan-shaped magnetic pole surface is the notch 5. In the state where the magnetic pole boundary L is located above, the magnetic pole boundary line L may happen to stop almost directly above the Hall element 3, and the dead point avoidance measure is still insufficient in terms of probability. In particular, in a mobile phone using this flat brushless motor as a flat vibration motor having an eccentric weight on the rotor, the magnetic pole boundary L is notched depending on the gravity direction of the eccentric weight accompanying the motor posture at the time of stoppage. Things that do not reach the top of 5 happen.

FIG. 12 is a partial plan view showing a state where the magnetic pole boundary line L is stopped just above the notch 5. This cutout portion 5 is fan-shaped magnetic pole (e.g., N pole) magnetic force lines emitted from the point P ₁ on the surface notches 5 of the meridian string path W to minimum point Q ₁ in a plan view of the upper edge 5a after reaching a ₁ for passing through the magnetic material plate 2, but contributes to the generation of active cogging torque component, while the direction of lines of magnetic force emitted from the point P ₂ on the pole face of the notch 5 arriving as a longitude line path W ₃ in the shortest point R ₂ on the chord line edge 5b of the notch 5 in the case to reach the string path W ₂ in a plan view in a plan view the shortest point Q ₂ on the diameter line edge 5a There are cases. This situation is the same for a point on the S pole that is symmetrical to the above point. For this reason, in the fan-shaped cutout portion 5, in the region E in which the radial path is substantially shorter than the chord path in plan view, the magnetic field lines only fly to the chord line edge 5b. It does not contribute substantially.

  Here, in order to increase the generation of cogging torque, it is conceivable that the notch 5 is formed deeper toward the center to lengthen the radial edge 5a. However, the enlargement of the notch area is not so large, and the magnetomotive force is weak in the vicinity of the magnetic pole boundary L, and even if the magnetic field lines through the chord path on the center side are slightly increased, the length of the arm that is the cause of torque generation As the length becomes shorter, the cogging torque is hardly increased. On the other hand, even when the notch 5 is formed wide in the arc direction and the notch occupying angle φ is increased, the region E that does not contribute to the generation of cogging torque still exists and the amount of leakage magnetic flux increases. The torque performance at the time deteriorates. Therefore, it is difficult to increase the cogging torque in the fan-shaped cutout portion 5 even if the width of the empty portion is enlarged.

  Therefore, in view of the above problems, an object of the present invention is to provide a flat brushless motor that can reliably avoid a dead point without deteriorating torque performance during energization.

  A flat brushless motor according to the present invention includes a stator magnetic plate on which a plurality of drive coils and magnetic pole detection elements that generate a rotating magnetic field are arranged side by side around a support shaft, where n is a natural number, and an arc angle of 180 ° / n An annular magnet having N-poles and S-poles alternately in the circumferential direction on the fan-shaped magnetic pole surface is disposed on the stator magnetic plate so as to face the surface, and includes a rotor that is rotatably supported with respect to the support shaft. In the region of the stator magnetic plate facing the annular magnet, the plane shape is bilaterally symmetric with respect to the hole center line passing through the rotation center of the rotor, and the position of the magnetic pole detection element and 180 ° / n with respect to this position A cogging torque generating hole having a hole center line at a position other than the divided position is provided, and a hole occupying angle (α) formed by a pair of tangent lines contacting the edge of the cogging torque generating hole from the rotation center is 180 ° / n or less, and the hole edge is formed inside the outer peripheral edge of the annular magnet.

  In the present invention, firstly, in the region of the stator magnetic plate facing the annular magnet, a notch is not formed on the outer peripheral side of the stator magnetic plate, but is surrounded by the ground plate of the stator magnetic plate. A cogging torque generating hole with a sharp hole edge is formed and an outer hole edge on the counter-rotating center side is formed. Therefore, when the rotor is stopped, the magnetic pole boundary line between the N pole and the S pole is In a state of being matched with the hole center line, a part of the magnetic force lines derived from the magnetic pole surface can reach the shortest point of the outer hole edge, so that the generation of cogging torque is enhanced. Therefore, effective cogging torque can be obtained by enlarging the cogging torque generating hole and setting the hole occupying angle (α) to a value close to 180 ° / n. In the state where the fan-shaped magnetic pole surface completely covers the cogging torque generating hole, the central portion of the fan-shaped magnetic pole surface where the magnetic force is the strongest overlaps with the vicinity of the center of the cogging torque generating hole, and the cogging torque is maximized. However, since the cogging torque generating hole can be made large and the ground plate part that overlaps the fan-shaped magnetic surface on both sides of the hole can be narrowed, the vicinity of the cogging torque maximum is steep with respect to the slight rotation angle of the rotor. It changes greatly and can be sharpened as a maximal point, thus effectively eliminating the idea of the rotor. For this reason, it is possible to reliably avoid the dead point.

  Second, the hole edge is formed inside the outer peripheral edge of the annular magnet. Magnetic field lines coming out from the outer peripheral surface of the annular magnet are also concentrated on the outer hole edge on the counter-rotation center side, so that leakage of magnetic flux can be suppressed and torque performance during energization does not deteriorate.

  Even when the cogging torque generating hole is formed large under the drive coil or the magnetic pole detection element, the cogging torque may be generated when no power is supplied. Space efficiency can be increased.

  It is desirable that the deviation angle (β) formed by the position of the magnetic pole detection element and the hole center line of the cogging torque generating hole nearest to the angle around the rotation center is not more than half of the hole occupation angle (α). When the rotor stops, the pole boundary line overlaps with the hole center line from the state where the magnetic pole boundary line overlaps one of the tangents of the hole edge, so that the rotor is reliably rotated with cogging torque for half the hole occupation angle (α). The Therefore, since the deviation angle (β) falls within half of the hole occupation angle (α), the magnetic pole boundary line does not stop at the position of the magnetic pole detection element. Note that 180 ° / n−α <β.

  Furthermore, the reason why the magnetic field lines from the point of the magnetic pole face that falls within the cogging torque generating hole reach the shortest point of only one point of the hole edge is that the hole edge is the inner arc edge on the rotation center side. It is desirable to include the outer arc edge on the counter-rotation center side, and the inner arc edge and outer arc edge of the same radius are connected by a straight edge even at the circumference of the circle where the inner arc edge and outer arc edge of the same radius are directly connected The oval edge may be a fan-shaped edge in which a small radius inner arc edge and a large radius outer arc edge are connected by a straight edge. The normal direction component of the magnetic pole boundary of the magnetic attractive force based on each point in the cogging torque generation hole contributes reliably to the generation of cogging torque, and almost no region that does not contribute to the generation of cogging torque can be eliminated. Torque can be increased.

  If there is only one cogging torque generating hole in the stator magnetic plate, the cogging torque may still be insufficient, and only one magnetic pole is excessively biased and magnetically attracted. It becomes unbalanced. In particular, when the rotor has an eccentric weight, the risk of surface blurring increases. Therefore, it is desirable that the stator magnetic plate is provided with n cogging torque generating holes having the same shape and having a hole center line at each rotationally symmetric position of 360 ° / n with respect to the rotation center. Cogging torque is generated in every other magnetic pole in a well-balanced manner, and the cogging torque is increased.

  In the case of n = 1, since the arc angle is an annular magnet having a fan-shaped magnetic pole surface of 180 °, it is difficult to make the hole occupation angle (α) close to the arc angle in terms of miniaturization. . In the case of n = 2, the arc angle is 90 °, and the hole occupation angle (α) can be theoretically set to 90 °, but the pulsation period due to the cogging torque is still long. In the case of n = 3, the arc angle is 60 °, and the hole occupation angle (α) can be theoretically set up to the arc angle of 60 °. In the case where n is 4 or more, the same principle can be set. However, since the deviation angle (β) is small, the position of the magnetic pole detection element is close to the magnetic pole boundary and the magnetism is weakened. Even if the magnetic pole boundary line vibrates slightly in the forward / reverse direction of the hole center due to impact or the like, there is a possibility that the rotor may be erroneously self-started in the reverse direction. The case where n = 3 is most desirable.

  When the rotor has an eccentric weight, it is suitable for use as a flat vibration motor. As described above, not only is it effective in avoiding a dead point, but the inertial motion of the rotor is strong at the time of stopping, but the braking action is activated by the generation of a strong cogging torque, and the duration of the inertial rotation can be shortened.

  According to the flat brushless motor of the present invention, it is possible to reliably avoid the dead point without deteriorating the torque performance during energization.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a perspective view showing a flat vibration motor according to an embodiment of the present invention, FIG. 2 is an assembly perspective view of the flat vibration motor, and FIG. 3 is a plan view showing a stator magnetic plate in the flat vibration motor. 4 is a perspective view of the stator magnetic plate, and FIG. 5 is a plan view showing a state where a flexible substrate for power feeding is superimposed on the stator magnetic plate.

  The flat (coin-shaped) vibration motor of this example is a brushless motor, and includes a stator magnetic plate 10 having a shaft receiver 11 and functioning as a yoke, and a support shaft 30 in which a washer 20 is stacked on the shaft receiver 11 and one end is press-fitted. And an integrated circuit for switching, which is thermally welded onto the stator magnetic plate 10 and has a central hole 41 and includes four air-core flat coils 42 to 45 for driving and a hall element (not shown) around the central hole 41. 46 and the capacitor 47 are mounted side by side, and a circular magnet 50 having a fan-shaped magnetic pole surface with an arc angle of 60 ° and alternately having N and S poles in the circumferential direction is arranged on the lower surface side, and an arc-shaped eccentric weight. 60 has an outer peripheral edge 60 and a radial bearing 70 at the center, and a rotor plate 80 that is rotatably supported by the support shaft 30 and a press-fitted and fixed to the other end of the support shaft 30. The lower end sexual plate 10 and a cover 90 of a magnetic material as a fixed yoke. The rotor plate 80 and the annular rotor magnet 50 constitute the rotor 100 corresponding to the stator magnetic plate 10.

  The power supply flexible board 40 has a protruding portion 48 having a power supply pattern (not shown) for soldering a lead wire (not shown) to the outside, and includes a capacitor 47, an integrated circuit for switching 46, and an air-flat coil 42 ~. Predetermined circuit wiring (not shown) for connecting the 45 terminals is formed.

The stator magnetic plate 10 is a flat plate obtained by press-molding a magnetic (ferromagnetic) plate made of iron or the like, and includes a substantially circular base plate portion 12 for forming a bottom plate of a flat vibration motor and a part on the outer peripheral side thereof. The terminal receiving plate portion 13 that protrudes and receives the protruding piece portion 48 of the power supply flexible substrate 40 is integrally provided. This stator magnetic plate 10 has three cogging torque generating round holes h having hole centers C _{1 to} C ₃ at rotationally symmetric positions of 120 ° with respect to the center C of the shaft receiver 11 (rotation center of the rotor 100) C. ₁ to h ₃ are formed. The round holes h _{1 to} h ₃ are perfect circles and have circumferential hole edges F _{1 to} F ₃ . The hole occupying angle α formed by the pair of tangents S ₁ and S ₂ that contact the edge F _{1 to} F ₃ of the cogging torque generating round holes h _{1 to} h ₃ from the center C is about an arc angle of 60 ° or less of the fan-shaped magnetic pole surface. 50 °.

Erected a support shaft 30 on the stator magnetic plate 10, while heat-welded onto superimposed correctly feeding flexible substrate 40 thereon, as shown in FIG. 5, the detection reference line m ₁ is the switching integrated circuits 46 The deviation angle β formed between the detection reference line m ₁ and the closest hole center C _{1 of the} cogging torque generating round hole h ₁ passes through the magnetic detection position of a built-in Hall element (not shown). The deviation angle β is less than half of the hole occupation angle α. For this reason, there is a cogging torque generating round hole h ₁ under the switching integrated circuit 46, and a cogging torque generating round hole h ₂ under the air core flat coils 42, 43, and the air core flat coils 44, 45. of it is cogging torque generating circular holes h ₃ below, does not overlap the hole center C _2, C ₃ the dividing line m _2, m ₃ divided 3 etc. relative to the detection reference line m _1, Similarly, it is separated by a deviation angle β. The cogging torque generating round holes h _{1 to} h ₃ are covered and closed by the power supply flexible substrate 40.

The positional relationship among the annular magnet 50, the stator magnetic plate 10, and the air flat coils 42 to 45 except for the rotor plate 80 and the power supply flexible substrate 40 with the rotor 100 attached to the support shaft 30 is shown in FIGS. It is shown in FIG. Although FIG. 6 cannot actually occur, the magnetic pole surface of the annular magnet 50 is directly above the air-core flat coils 42 to 45, and the magnetic boundary line L is the detection reference line m ₁ or the dividing lines m ₂ and m ₃ . The dead point state where it stopped on top of it is shown. Of the hole edges F _{1 to} F ₃ of the cogging torque generating round holes h _{1 to} h ₃ , edge parts f _{1 to} f ₃ on the rotation center side slightly protrude inward from the inner peripheral edge 50 a of the annular magnet 50. The entire arrangement of the hole edges F _{1 to} F ₃ is located on the inner side from the outer peripheral edge 50 b of the annular magnet 50.

Figure 7 shows the actual stop position the annular magnet 50 is avoided arrest at dead point, the magnetic boundary line L overlaps the hole center C ₁ -C ₃ in the cogging torque generated by the round holes h ₁ to h ₃ It is in the state. In such a state, as shown in FIG. 9, the lines of magnetic force emitted from any of the points P _{1 to} P ₃ on the magnetic pole (for example, the N pole) plane pass through the radial path and are the only shortest points T _{1 to} T of the hole edge F _{1. 3} and passes through the stator magnetic plate 10. A region in the normal direction of the magnetic pole boundary L of the magnetic attractive force based on each point in the cogging torque generating round holes h _{1 to} h ₃ surely contributes to the generation of the cogging torque and does not contribute to the generation of the cogging torque. It can be almost eliminated and the cogging torque can be increased.

When the annular magnet 50 is stopped, since the magnetic pole boundary line L overlaps with one of the tangents S ₁ and S ₂ of the hole edges F _{1 to} F ₃ and stops with the hole centers C _{1 to} C ₃ , During the half of the occupation angle (α), the annular magnet 50 is reliably rotated by the cogging torque. Therefore, since the deviation angle β falls within half the hole occupation angle (α), the magnetic pole boundary L does not stop on the detection reference line m ₁ or the dividing lines m ₂ and m ₃ .

The hole edges F _{1 to} F ₃ are formed inside the outer peripheral edge 50 b of the annular magnet 50. For this reason, the lines of magnetic force emerging from the outer peripheral surface of the annular magnet 50 are also concentrated on the outer hole edge on the counter-rotation center side of the hole edges F _{1 to} F ₃ , so that magnetic flux leakage can be suppressed and torque performance during energization is deteriorated. You don't have to invite me.

FIG. 8 shows a state in which the fan-shaped magnetic pole surface completely covers the cogging torque generating round holes h _{1 to} h ₃ . This state is when the center of the magnetic force of the fan-shaped magnetic pole surface and the center of the hole overlap each other, and the cogging torque is maximized, but the cogging torque generating round holes h _{1 to} h ₃ are formed to be large and the hole Since the occupation angle α can be set large, the width of the ground plate portion of the stator magnetic plate 10 that overlaps the fan-shaped magnetic pole surface (the range within the angle γ formed by the tangents S ₁ and S ₂ and the magnetic pole boundary L) is about 5 °. Since it is limited to a narrow range, the vicinity of the cogging torque maximum changes sharply and greatly with respect to a small rotation angle of the rotor 100, and can be sharpened as a maximum point. Therefore, the idea of the rotor can be effectively eliminated. Since the hole occupation angle α can be set large, the thought point of the annular magnet 50 at this position can be effectively eliminated. For this reason, it is possible to reliably avoid the dead point. Here, the relationship of 2γ <β is established.

Note that the hole shape of the hole for generating the cogging torque is not limited to a round hole, and as shown in FIG. 10A, the hole shape is symmetrical with respect to the hole center line (symmetry axis) X passing through the center C and has the same radius. An elliptical edge in which the inner arc edge D ₁ and the outer arc edge D ₂ are connected by straight edges G ₁ and G ₂ as tangents, and as shown in FIG. 10B, the inner arc edge d _{1 having} a small radius is also provided. And an outer arc edge D ₂ having a large radius may be fan-shaped edges connected by radial line edges (straight edges) G ₁ ′, G ₂ ′ as tangent lines.

It is a perspective view which shows the flat vibration motor which concerns on the Example of this invention. It is an assembly perspective view of the flat vibration motor. It is a top view which shows the stator magnetic plate in the flat vibration motor. It is a perspective view of the stator magnetic plate. It is a top view which shows the state which piled up the flexible substrate for electric power feeding on the stator magnetic plate. It is a top view which shows the dead point of the rotor in the same flat vibration motor. It is a top view which shows the stop position of the rotor in the flat vibration motor. It is a top view which shows the state in which the magnetic pole of the rotor in the same flat vibration motor covers the round hole for cogging torque generation. It is a partial top view which expands and shows the round hole for cogging torque generation in the stop position of the rotor. It is a top view which shows the hole for cogging torque generation of another hole shape in the same stator magnetic plate. (A) is a top view which shows the conventional flat brushless motor, (B) is an enlarged side view which shows the notch part of the magnetic material plate. It is a fragmentary top view which expands and shows a notch part in the same flat brushless motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Toroidal magnet 2 ... Magnetic material plate 3 ... Hall element 4 ... Drive coil 5 ... Notch part 5a ... Radius edge 5b ... String line edge 10 ... Stator magnetic plate 11 ... Shaft support 12 ... Base plate part 13 ... Terminal Back plate 20 ... Washer 30 ... Support shaft 40 ... Power supply flexible substrate 41 ... Central hole 42 to 45 ... Air-core flat coil 46 ... Switching integrated circuit 47 ... Capacitor 48 ... Projection piece 50 ... Round magnet 50a ... Inner circumference side edge 50b ... outer peripheral edge 60 ... eccentric weights 70 ... radial bearing 80 ... rotor plate 90 ... cover 100 ... rotor C ... rotation center _C 1 -C 3 _... hole center _{D 1,} d 1 _... inner arc edge _{D 2} ... outer Arc edge E: Area F _{1 to} F ₃ not contributing to cogging torque generation Hole edge f _{1 to} f ₃ ... Edge portion G ₁ , G ₂ ... Linear edge G ₁ ', G ₂ ' ... Radial edge h _{1 to} h ₃ ... cogging torque Generating round hole L ... pole boundary line (magnetic neutral point)
m ₁ ... detection reference lines m ₂ , m ₃ ... dividing line O ... notch center line (symmetric axis)
P _{1 to} P ₃ ... Points Q ₁ , Q ₂ , R ₂ , T _{1 to} T ₃ on the magnetic pole surface ... Shortest points S ₁ , S ₂ ... Tangential lines W ₁ , W ₂ ... String path W ₃ ... Diameter path X ... Hole centerline (axis of symmetry)
α ... hole occupation angle β, θ ... deviation angle φ ... notch occupation angle γ ... angle formed by tangent and magnetic pole boundary line

Claims (8)

n is a natural number, a stator magnetic plate on which a plurality of drive coils and magnetic pole detection elements that generate a rotating magnetic field are arranged around a support shaft, and a fan-shaped magnetic pole surface with an arc angle of 180 ° / n. In a flat brushless motor provided with an annular magnet having alternating turns in a circumferential direction, faced to the stator magnetic plate, and a rotor supported rotatably with respect to the support shaft,
The region of the stator magnetic plate facing the annular magnet has a plane shape that is symmetrical with respect to the center line of the hole passing through the rotation center of the rotor, and the position of the magnetic pole detection element and 180 ° / a cogging torque generating hole having the hole center line at a position excluding a position equally divided by n, and a hole occupying angle formed by a pair of tangent lines contacting the edge of the cogging torque generating hole from the rotation center ( α) is 180 ° / n or less, and the hole edge is formed inside the outer peripheral edge of the annular magnet. 2. The flat brushless motor according to claim 1, wherein a deviation angle (β) formed by the position of the magnetic pole detection element and the hole center line of the cogging torque generating hole closest thereto at an angle around the rotation center is as follows. A flat brushless motor having a hole occupation angle (α) of less than half. 3. The flat brushless motor according to claim 1, wherein the hole edge includes an inner arc edge on the rotation center side and an outer arc edge on the counter rotation center side. 4. 4. The flat brushless motor according to claim 3, wherein the hole edge is a circular periphery. 4. The flat brushless motor according to claim 3, wherein the inner arc edge and the outer arc edge are connected by a straight edge. 6. The flat brushless motor according to claim 1, wherein the stator magnetic plate has an isomorphous n having the hole center line at each rotationally symmetric position of 360 ° / n with respect to the rotation center. A flat brushless motor comprising a plurality of cogging torque generating holes. 7. The flat brushless motor according to claim 6, wherein n = 3. The flat brushless motor as defined in any one of claims 1 to 7, wherein the rotor has an eccentric weight.

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